jQuery.extend({
    createUploadIframe: function(id, uri)
    {
         //create frame
        var frameId = 'jUploadFrame' + id;
        
        if(window.ActiveXObject) {
            var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
            if(typeof uri== 'boolean'){
                io.src = 'javascript:false';
            }
            else if(typeof uri== 'string'){
                io.src = uri;
            }
        }
        else {
            var io = document.createElement('iframe');
            io.id = frameId;
            io.name = frameId;
        }
        io.style.position = 'absolute';
        io.style.top = '-1000px';
        io.style.left = '-1000px';
        
        document.body.appendChild(io);
        
        return io			
    },
    createUploadForm: function(id, fileElementId,elems)
    {
        //create form	
        var formId = 'jUploadForm' + id;
        var fileId = 'jUploadFile' + id;
        var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');	
        var oldElement = jQuery('#' + fileElementId);
        var newElement = jQuery(oldElement).clone();
        jQuery(oldElement).attr('id', fileId);
        jQuery(oldElement).before(newElement);
        jQuery(oldElement).appendTo(form);
        jQuery(elems).appendTo(form);
        //set attributes
        jQuery(form).css('position', 'absolute');
        jQuery(form).css('top', '-1200px');
        jQuery(form).css('left', '-1200px');
        jQuery(form).appendTo('body');		
        return form;
    },
    createUploadFormData: function(data)
    {
        var elems;
        
        for (var d in data)
        {
            elems+='<input type="hidden" name="'+d+'" value="'+data[d]+'" />';
        }
        
        return elems;
    },
    ajaxFileUpload: function(s) {
        // TODO introduce global settings, allowing the client to modify them for all requests, not only timeout		
        s = jQuery.extend({}, jQuery.ajaxSettings, s);
        var id = new Date().getTime();
        var elems = jQuery.createUploadFormData(s.data);
        var form = jQuery.createUploadForm(id, s.fileElementId,elems);
        var io = jQuery.createUploadIframe(id, s.secureuri);
        var frameId = 'jUploadFrame' + id;
        var formId = 'jUploadForm' + id;		
        
        // Watch for a new set of requests
        if ( s.global && ! jQuery.active++ )
        {
        	jQuery.event.trigger( "ajaxStart" );
        }         
           
        var requestDone = false;
        // Create the request object
        var xml = {}   
        if ( s.global )
            jQuery.event.trigger("ajaxSend", [xml, s]);
        // Wait for a response to come back
        var uploadCallback = function(isTimeout)
    	{			
    		var io = document.getElementById(frameId);
            try 
            {				
            	if(io.contentWindow)
            	{
                        xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
                        xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
            	}else if(io.contentDocument)
            	{
                        xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
                        xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
            	}						
            }catch(e)
            {
            	jQuery.handleError(s, xml, null, e);
            }
            
            if ( xml || isTimeout == "timeout") 
            {				
                requestDone = true;
                var status;
                try {
                    status = isTimeout != "timeout" ? "success" : "error";
                    // Make sure that the request was successful or notmodified
                    if ( status != "error" )
                    {
                        // process the data (runs the xml through httpData regardless of callback)
                        var data = jQuery.uploadHttpData( xml, s.dataType );    
                        // If a local callback was specified, fire it and pass it the data
                        if ( s.success )
                            s.success( data, status );
    
                        // Fire the global callback
                        if( s.global )
                            jQuery.event.trigger( "ajaxSuccess", [xml, s] );
                    } else
                        jQuery.handleError(s, xml, status);
                } catch(e) 
                {
                    status = "error";
                    jQuery.handleError(s, xml, status, e);
                }
    
                // The request was completed
                if( s.global )
                    jQuery.event.trigger( "ajaxComplete", [xml, s] );
    
                // Handle the global AJAX counter
                if ( s.global && ! --jQuery.active )
                    jQuery.event.trigger( "ajaxStop" );
    
                // Process result
                if ( s.complete )
                    s.complete(xml, status);
    
                jQuery(io).unbind()
    
                setTimeout(function()
                {	try 
                	{
                            jQuery(io).remove();
                            jQuery(form).remove();	
                		
                	} catch(e) 
                	{
                            jQuery.handleError(s, xml, null, e);
                	}									
                
                }, 100)
    
                xml = null
    
            }
        }
        // Timeout checker
        if ( s.timeout > 0 ) 
    	{
            setTimeout(function(){
                // Check to see if the request is still happening
                if( !requestDone ) uploadCallback( "timeout" );
            }, s.timeout);
        }
        try 
    	{
           // var io = jQuery('#' + frameId);
            var form = jQuery('#' + formId);
            jQuery(form).attr('action', s.url);
            jQuery(form).attr('method', 'POST');
            jQuery(form).attr('target', frameId);
            if(form.encoding)
    		{
                form.encoding = 'multipart/form-data';				
            }
            else
    		{				
                form.enctype = 'multipart/form-data';
            }			
            jQuery(form).submit();
    
        } catch(e) 
    	{			
            jQuery.handleError(s, xml, null, e);
        }
        if(window.attachEvent){
            document.getElementById(frameId).attachEvent('onload', uploadCallback);
        }
        else{
            document.getElementById(frameId).addEventListener('load', uploadCallback, false);
        } 		
        return {abort: function () {}};	
    
    },
    
    uploadHttpData: function( r, type ) {
        var data = !type;
        data = type == "xml" || data ? r.responseXML : r.responseText;
        // If the type is "script", eval it in global context
        if ( type == "script" )
            jQuery.globalEval( data );
        // Get the JavaScript object, if JSON is used.
        if ( type == "json" )
            eval( "data = " + data );

        if ( type == "html" )
            jQuery("<div>").html(data);
            
        return data;
    }
});

